<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
    <title>Document</title>
    <link rel="stylesheet" href="./css/main.css">
</head>
<body>
<form action="index.php" method="post">
    <input type="text" name="mu1">
    <select  name="fh">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">*</option>
        <option value="/">/</option>
    </select>
    <input type="text" name="mu2">
    <input type="submit" class="btn">
    <?php
    if($_POST !=null){
        $mu1= intval($_POST['mu1']);
        $mu2= intval($_POST['mu2']);
        $fh= $_POST['fh'];
        switch($fh){
            case  "+":
                echo"<h3>$mu1 加 $mu2 等于 " .($mu1+$mu2). "</h3>";
                break;
            case  "-":
                echo"<h3>$mu1 减 $mu2 等于 " .($mu1-$mu2). "</h3>";
                break;
            case  "*":
                echo"<h3>$mu1 乘 $mu2 等于 " .($mu1*$mu2).  "</h3>";
                break;
            case  "/":
                echo"<h3>$mu1 除 $mu2 等于 " .($mu1/$mu2). "</h3>";
                break;
        }
    }
    ?>
</form>
</body>
</html>
